diff --git a/app/controllers/related_contents_controller.rb b/app/controllers/related_contents_controller.rb
index bbb391465..e6ebac6b0 100644
--- a/app/controllers/related_contents_controller.rb
+++ b/app/controllers/related_contents_controller.rb
@@ -4,18 +4,20 @@ class RelatedContentsController < ApplicationController
   respond_to :html, :js
 
   def create
-    if relationable_object && related_object
-      if relationable_object != related_object
-        RelatedContent.create!(parent_relationable: @relationable, child_relationable: @related, author: current_user)
+    related_content = RelatedContent.new(
+      parent_relationable: relationable_object,
+      child_relationable: related_object,
+      author: current_user
+    )
 
-        flash[:success] = t("related_content.success")
-      else
-        flash[:error] = t("related_content.error_itself")
-      end
+    if related_content.save
+      flash[:success] = t("related_content.success")
+    elsif related_content.same_parent_and_child?
+      flash[:error] = t("related_content.error_itself")
     else
       flash[:error] = t("related_content.error", url: Setting["url"])
     end
-    redirect_to polymorphic_path(@relationable)
+    redirect_to polymorphic_path(relationable_object)
   end
 
   def score_positive
@@ -40,7 +42,7 @@ class RelatedContentsController < ApplicationController
     end
 
     def relationable_object
-      @relationable = params[:relationable_klass].singularize.camelize.constantize.find_by(id: params[:relationable_id])
+      @relationable ||= params[:relationable_klass].singularize.camelize.constantize.find_by(id: params[:relationable_id])
     end
 
     def related_object
@@ -51,7 +53,7 @@ class RelatedContentsController < ApplicationController
                            .flatten.map { |i| i.to_s.singularize.camelize }.join("::")
         related_id = url.match(/\/(\d+)(?!.*\/\d)/)[1]
 
-        @related = related_klass.singularize.camelize.constantize.find_by(id: related_id)
+        related_klass.singularize.camelize.constantize.find_by(id: related_id)
       end
     rescue
       nil
diff --git a/app/models/related_content.rb b/app/models/related_content.rb
index 8a81413ed..c383bf376 100644
--- a/app/models/related_content.rb
+++ b/app/models/related_content.rb
@@ -16,6 +16,7 @@ class RelatedContent < ApplicationRecord
   validates :child_relationable_id, presence: true
   validates :child_relationable_type, presence: true
   validates :parent_relationable_id, uniqueness: { scope: [:parent_relationable_type, :child_relationable_id, :child_relationable_type] }
+  validate :different_parent_and_child
 
   after_create :create_opposite_related_content, unless: proc { opposite_related_content.present? }
   after_create :create_author_score
@@ -34,8 +35,18 @@ class RelatedContent < ApplicationRecord
     related_content_scores.exists?(user: user)
   end
 
+  def same_parent_and_child?
+    parent_relationable == child_relationable
+  end
+
   private
 
+    def different_parent_and_child
+      if same_parent_and_child?
+        errors.add(:parent_relationable, :itself)
+      end
+    end
+
     def create_opposite_related_content
       related_content = RelatedContent.create!(opposite_related_content: self, parent_relationable: child_relationable,
                                                child_relationable: parent_relationable, author: author)
diff --git a/spec/models/related_content_spec.rb b/spec/models/related_content_spec.rb
index 557ff3e53..75d540624 100644
--- a/spec/models/related_content_spec.rb
+++ b/spec/models/related_content_spec.rb
@@ -25,6 +25,14 @@ describe RelatedContent do
     expect(new_related_content).not_to be_valid
   end
 
+  it "does not allow relating a content to itself" do
+    related_content = build(:related_content,
+                            parent_relationable: parent_relationable,
+                            child_relationable: parent_relationable)
+
+    expect(related_content).not_to be_valid
+  end
+
   describe "create_opposite_related_content" do
     let(:parent_relationable) { create(:proposal) }
     let(:child_relationable) { create(:debate) }